11 February 2009

Birth defects linked to obesity during pregnancy

by Kate Melville

Women who are obese during pregnancy are putting their child at risk of birth defects such as spina bifida, heart defects, cleft palate, brain defects and gastrointestinal defects, according to a new study in the Journal of the American Medical Association.

To assess the relationship between maternal overweight and obesity and the risk of congenital anomaly in newborns, Katherine J. Stothard and colleagues from Newcastle University in the U.K. conducted a review and meta-analysis of past studies. The research team identified 39 articles that were included in a systematic review and 18 articles in the meta-analysis.

"In women who were obese at the start of pregnancy, the meta-analysis demonstrated a significantly increased risk of a pregnancy affected by a neural tube defect [nearly twice the odds], including spina bifida [more than twice the odds]; cardiovascular anomaly, including a septal anomaly [heart defect]; cleft palate and cleft lip and palate; anorectal atresia [abnormality of the anus/rectum]; hydrocephaly [abnormal enlargement of the ventricles of the brain due to accumulation of cerebrospinal fluid]; and a limb reduction anomaly," the study notes.

Putting the findings into perspective, Stothard noted that an estimated 3 percent of all livebirths in the United States are affected by a structural anomaly and 2.25 per 1,000 births are affected by a serious heart anomaly. "Given the findings of this review... we calculate that the absolute risk of a pregnancy affected by a neural tube defect or a serious heart anomaly is respectively 0.47 per 1,000 births and 0.61 per 1,000 births greater in an obese woman than a woman of recommended BMI in prepregnancy or early pregnancy. This has health implications, particularly given the continued rise in the prevalence of obesity in many countries," she explained, adding that "further studies are needed to confirm whether [maternal] overweight is also implicated."

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Source: Journal of the American Medical Association